Begins with a historical overview by Henry Taube. Overviews the advances pioneered by Taube, including mechanisms of electron transfer reactions, charge transfer complexes, and *p back bonding effects in metal-ligand interactions. Discusses applications of principles of electron transfer to diverse areas of chemistry and biology such as the selective and controlled oxidation of organic functional groups, polymerization catalysis, metal biological interactions with DNA, biological electron transfer reactions, and new imaging agents in diagnostic medicine.